Congolese police fired warning shots to disperse rioting opposition protesters in Kinshasa who tore down election posters, threatened foreigners and demanded the postponement of historic polls set for Sunday.
The several thousand demonstrators, who want Democratic Republic of Congo's first multi-party polls in 40 years to be delayed because of political tensions and accusations of flaws, threw rocks and petrol bombs, blocking a highway into the city.
Chanting "Congo is for the Congolese", they accused the international community supporting the landmark elections of trying to engineer a victory for President Joseph Kabila. He is viewed as the frontrunner out of 32 presidential candidates.
Some threatened to kill foreigners, making a gesture to foreign reporters of drawing their fingers across their throats.
Plain clothes police officers fired warning shots into the air. Riot police also fired tear gas at the protesters, who shut off the main road from Kinshasa's international airport.
A Reuters reporter saw officers arrest and beat several protesters with batons, including one woman. One police officer was seen bleeding from the head after being struck by a stone.
Black-uniformed members of the elite presidential guard, armed with AK-47 automatic rifles and grenade launchers, were deployed. There was no immediate information about casualties.
The clashes were certain to increase fears that violence could disrupt voting in Sunday's landmark presidential and parliamentary polls in the vast, mineral-rich but war-scarred former Belgian colony in central Africa.
The elections are being supervised and protected by the largest UN peacekeeping force in the world at a cost of more than $400 million.
Voting will take place against a backdrop of simmering violence from rebels and renegade militias who continue to kill, rape and loot in many areas, especially the east, despite the official end three years ago of a devastating 1998-2003 war.
"There is no question of having these elections. They have been imposed by the international community. We are going to chase Joseph (Kabila) and we are going to kill you whites," one protester yelled at reporters as he ran past.
In a separate incident in the central market, 15 people were injured when a Congolese army soldier accidentally dropped a hand grenade while boarding a bus, UN officials said.
The demonstrators tore down election posters for Kabila and other candidates that festoon much of Kinshasa. Some dangled by the legs a dog dressed in a Kabila campaign T-shirt.
The protest, the latest of several violent demonstrations, followed complaints by the country's powerful Roman Catholic Church and several election candidates that serious irregularities marred the organisation of the polls.
"The international community says this is a new stage in Congo's history but we think the atmosphere is tense and dangerous," Remy Masamba, secretary-general of the opposition UDPS party, said.
"We want the elections to be delayed so they can be more inclusive and transparent."
The complaints have focused on the printing of excess ballot papers and missing voter registration details, which Kabila's opponents say are a sign of imminent fraud.
The UDPS, led by veteran opposition politician Etienne Tshisekedi, has called for a boycott of the polls.
On Sunday, when Kabila made a campaign visit to a UDPS stronghold outside Kinshasa, riot police also dispersed stone-throwing demonstrators.